Embodiments of the disclosure relate generally to methods and systems for manufacturing large components and more particularly, to methods and systems for forming composite structures to close tolerances.
Manufacturing techniques for assembling large structures from composite material use massive tooling to provide a stable platform to form the structure. Determinant assembly (DA) holes or other indexing features are use to fix locations of the structure relative of points of reference. The DA holes permit accurately ascertaining the location of any point on the structure surface. Such accurate location may be needed when further manufacturing processes are performed on the structure after the initial forming process. Such further processes may include cutting apertures at predetermined locations or milling certain features into the surface of the structure. However, the massive tooling may introduce an amount of sag into the structure that will be removed from the structure when the tooling is disassembled and the structure becomes free standing. For example, an airplane fuselage barrel may be formed of composite material wound around tooling. The tooling may be massive enough to sag between the points of rotation at either end of the tooling. As the structure is formed, it acquires the sag from the tooling. Before the formed barrel is removed from the tooling, typically window, and door apertures and attachment fixtures are cut into the barrel. If the apertures are cut into the barrel in a sag state, the apertures will be mispositioned when the tooling is removed and the barrel conforms to its nominal or unflexed shape.
What are needed are methods and systems for providing accurate placement of apertures and fixtures to manufactured parts that may flex during manufacturing.